There are a number of medical, diagnostic, and research procedures that require the use of needles. During use the needles come in contact with pathogens or toxic materials that are harmful to subjects, researchers, and medical practitioners.
For example, many different kinds of medical procedures require that a needle be inserted into a subject thereby coming into contact with the subject's fluids, blood, or other tissues. Such a needle may be present in conjunction with a wide variety of other devices, including, but not limited to, syringes, catheters, and introducers. In the medical field, the needle is typically intended for bodily penetration. Once it comes into contact with the subject's tissues, the needle becomes contaminated and extremely dangerous. A contaminated needle may transmit one or more of many different forms of blood-transmitted diseases, including, for example, the HIV virus, the hepatitis B virus, and the like. Hence, a contaminated needle is dangerous and in fact potentially deadly.
Many different safety techniques have been suggested for dealing with contaminated needles. One safety technique attempts to automatically insert a cover over the needle end when the needle is removed from contact with the patient (see, e.g., U.S. Pat. Nos. 5,053,017; 5,312,345; 5,688,249; and 6,117,108). This system may still allow contact with parts of the needle, which may have blood or tissue on them, even though it may cover the needle end.
Another safety technique allows the needle to be retracted into a housing after removal (see, e.g., U.S. Pat. Nos. 4,747,831; 4,950,252; 5,215,528; and 5,273,540). This system has advantages because the needle is totally encased within the housing when in a safe position. However, the needle may be pulled from the patient without actually being in a safe position. In other words, operator error may lead to an unsafe condition in which a contaminated needle is exposed.